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Publication numberUS4247747 A
Publication typeGrant
Application numberUS 06/018,422
Publication dateJan 27, 1981
Filing dateMar 7, 1979
Priority dateMar 15, 1978
Also published asCA1102767A1, DE2910055A1
Publication number018422, 06018422, US 4247747 A, US 4247747A, US-A-4247747, US4247747 A, US4247747A
InventorsRoyston W. Swatten
Original AssigneeDecca Limited
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Illuminated panels
US 4247747 A
Abstract
A self-illuminating panel in which characters are unobtrusively illuminated by projection of light into a narrow face of a transparent flexible lamina marked with the characters. Each character, which may be a translucent printed figure, provides an optical discontinuity which disperses the light so that the diffusely illuminated character can be viewed in contrast against a dark background behind the lamina. Pressure applied on and through the flexible lamina enables operation of an array of switches disposed behind the lamina.
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Claims(6)
I claim:
1. A self-illuminating panel comprising:
(a) a transparent flexible lamina, said lamina bearing markings which constitute optical discontinuities that define visible characters;
(b) an optical source which projects light into the lamina through a narrow face thereof;
(c) an opaque flexible screen which is disposed behind the lamina and spaced therefrom; and
(d) an array of pressure-operable switches disposed behind said screen, said switches being in register with said characters and each operable by the application of pressure on the lamina.
2. A switch panel according to claim 1 in which the lamina is less than 0.3 mm in thickness.
3. A switch panel according to claim 1 in which a mask is disposed in front of the lamina, said mask having apertures which expose the markings on the lamina.
4. A switch panel according to claim 1 further comprising a spring sheet disposed behind the screen.
5. A switch-panel according to claim 1 in which the optical source comprises a plurality of light emitters aligned on opposite narrow faces of the lamina, and each emitter projects light into the lamina at a point offset with respect to the two nearest markings on the lamina.
6. A self-illuminating panel comprising:
(a) a transparent flexible lamina, said lamina bearing rows of markings which constitute optical discontinuities that define visible characters;
(b) an optical source for projecting light into the lamina through a narrow face thereof, said source comprising a plurality of light emitters each offset from said rows;
(c) an opaque flexible screen disposed behind and spaced from said lamina;
(d) a flexible spring sheet disposed behind said screen;
(e) an array of pressure operable switches in register with particular characters, said switches being operable by pressure applied to said lamina and through said screen and spring sheet; and
(f) a mask disposed in front of said lamina, said mask having apertures for exposing said markings.
Description
BACKGROUND OF THE INVENTION

The invention described relates to illumination of panels, in particular, but not exclusively, to press button switch-panels of which the indicators are illuminated unobtrusively whatever the intensity of the ambient light might be.

SUMMARY OF THE INVENTION

According to the invention there is provided a self-illuminating panel comprising a transparent flexible lamina, an optical source which projects light into the lamina through a narrow face thereof, the lamina bearing markings which constitute optical discontinuities that define visible characters, and an opaque screen which is behind the lamina and is spaced therefrom.

In a preferred embodiment an array of switches is disposed behind the screen, the switches being operable by the application of pressure on and through the lamina and screen.

The characters, which may be in approximate register with the locations of the switches, may be exposed by apertures in a mask disposed in front of the lamina. The characters may be translucent and printed on the obverse, or preferably the reverse of the lamina. The switches may be operable by a spring sheet disposed behind the lamina. The screen is preferably an opaque flexible sheet interposed between the lamina and the spring sheet but could be constituted by the spring sheet itself. The lamina is preferably less than 0.3 mm in thickness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a plan view of a switch panel, and

FIG. 2 is an expanded isometric view of the switch panel of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2 an inflexible switch cover or mask 1, made of metal, plastics or other materials, has suitable openings 2, to provide switch button access, through which a transparent lamina 3 may be viewed. This cover may be hinged at one end to enable access to the surface of the film beneath and facilitate cleaning. Behind each of the openings 2 of the cover the lamina 3 is marked with symbols 4 indicating the switch to be operated. Marking of the symbols on the lamina is by silk-screen printing or other suitable method of marking which provide a translucent surface or impression on or in optical contact with the lamina. White is an effective colour for such symbols which may be marked on the back surface of the lamina for protection and so that the lamina is easier to clean. A polyester film such as "Mylar" film having a thickness of 0.007 inches is a suitable material for the transparent lamina. At one or more edges of the lamina 3 there are strips 5 made of metal, plastics or other suitable materials having a slot 6 along one edge to receive the edge of the lamina 3, and suitable mounting spaces 7 to receive illumination means such as high intensity light emitting diodes 8. Such an arrangement provides edge lighting for the lamina, the strip 5 serving the purpose of restricting the light to the required area and providing supporting means for the lamina. Red light is particularly favoured for applications where maintenance of `night-vision` is required.

When using an illumination system comprising a number of separate light sources it is desirable that the light sources should not be located directly in line with the symbols, as this results in uneven illumination due to the symbols first in line in the light path receiving and emitting a greater intensity of light than those subsequent. A flexible screen 9 with a black surface facing lamina 3 provides a dark background against which the symbols may be viewed. There should be no contact and hence no optical contact between the sheet 9 and lamina 3, or the lamina 3 and cover 1.

An embossed spring sheet 10 is preferably located behind sheet 9 to provide a snap action for switches of which the terminals are disposed on a circuit board 11. Between spring sheet 10 and circuit board 11 a second `Mylar` lamina 12 of, for example, 0.1 mm thickness acts as a spacer. This lamina 12 has apertures 13 through which the corresponding regions of the spring sheet 10 can contact the circuit board 11 when depressed. It will be readily apparent that a self illuminating panel according to the invention may be incorporated in a hand computer in which such an embossed spring sheet is common-place. Other forms of pressure-responsive switches could be used.

Each switch is operated by the insertion of a member, such as a finger into the aperture: the lamina, screen and sheet are sufficiently flexible to be brought together locally when a switch is operated.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2648305 *Feb 25, 1950Aug 11, 1953Westinghouse Electric CorpIlluminated indicating control
US2839670 *Jan 18, 1957Jun 17, 1958Lewis GladstoneIlluminated cover plate for electrical outlets
US3027669 *Nov 30, 1959Apr 3, 1962George K C HardestyIllumination system for instrument panel display
US3321616 *Jan 11, 1965May 23, 1967Adler Ronald EIlluminated sketch and memo board
US3862381 *Oct 29, 1973Jan 21, 1975Chomerics IncKeyboard switch assembly with multilayer, coextensive contactor means
US4060703 *Nov 10, 1976Nov 29, 1977Everett Jr Seth LeroyKeyboard switch assembly with tactile feedback having illuminated laminated layers including opaque or transparent conductive layer
US4158115 *Jun 26, 1978Jun 12, 1979W. H. Brady Co.Internally connecting flexible switch
US4163138 *Mar 17, 1978Jul 31, 1979Bowmar Instrument CorporationFlush lighted flat keyboard assembly
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4343975 *Dec 1, 1980Aug 10, 1982Shin-Etsu Polymer Co., Ltd.Key board switch unit with illumination
US4796007 *Jan 5, 1987Jan 3, 1989Ncr CorporationMicro-motion keyboard
US5073843 *Oct 31, 1990Dec 17, 1991Magee Vera CPhosphorescent key pad
US5118910 *Mar 12, 1990Jun 2, 1992Tapeswitch Corporation Of AmericaIlluminated, pressure-actuated switch
US5128842 *Jun 3, 1991Jul 7, 1992Sunarrow Co., Inc.Uniform illumination plate
US5260530 *May 29, 1992Nov 9, 1993Tapeswitch Corporation Of AmericaIlluminated, pressure-actuated switch
US5698826 *Sep 25, 1996Dec 16, 1997Maytag CorporationSelective back lighting of appliance control panel
US5975711 *Jun 9, 1997Nov 2, 1999Lumitex, Inc.Integrated display panel assemblies
US6158867 *Oct 7, 1998Dec 12, 2000Lumitex, Inc.Light emitting panel assemblies for use in automotive applications and the like
US6367940 *Oct 31, 2000Apr 9, 2002Solid State Opto LimitedLight emitting panel assemblies for use in automotive applications and the like
US6861600Oct 1, 2003Mar 1, 2005Lumitex, Inc.Integrated switch and backlight assembly
US7690803 *Aug 3, 2007Apr 6, 2010Citizen Electronics Co., Ltd.Light emitting sheet module
US7789519 *Feb 16, 2006Sep 7, 2010BSH Bosch uns Siemens Hausgeraete GmbHIlluminated display window for LED and/or LC displays
US8371734Sep 17, 2010Feb 12, 2013Rogers CorporationFront lit alterable display
US8540384Feb 7, 2011Sep 24, 2013Andrew J. Katrinecz, Jr.Low power low cost illuminated keyboards and keypads
EP0763838A1 *Jun 13, 1996Mar 19, 1997Fuji Polymertech Co., LtdIlluminated switches
EP0801373A1 *Jan 7, 1997Oct 15, 1997Lumitex, Inc.Light emitting panel assemblies for use in automotive applications and the like
WO2003071565A1 *Jan 15, 2003Aug 28, 2003Mineur BoIlluminated control
Classifications
U.S. Classification200/314, 200/317, 200/5.00A
International ClassificationG09F13/18, H01H13/83, G09F9/00
Cooperative ClassificationG09F2013/1831, H01H2219/014, H01H2223/034, H01H13/83, H01H2219/04, H01H2229/062, H01H2219/028, G02B6/0091, H01H2219/044
European ClassificationG02B6/00L6U6R, H01H13/83